An application for recognizing a word or phrase produced by a speaker from an audio signal and translating the recognized word or phrase into another language, or searching the recognized word or phrase as a query on a network or a database has been developed. In such application, to identify an interval in which the speaker is producing a speech, for example, the speaker is requested to operate the apparatus that installs with such application therein to instruct start and end of recording of the audio signal. However, in some environments where such application is used, the speaker may not perform the above-mentioned operation. For example, when the speaker is using his/her both hands, the speaker is not able to perform the operation of instructing start and end of recording of the audio signal.
Another technique of determining presence or absence of sound in an audio signal has been proposed. According to this technique, power and a pitch parameter of the input audio signal are calculated for every fixed interval of the audio signal. When a pitch parameter of a second fixed interval following a first sound fixed interval is lower than a predetermined threshold, the second fixed interval is determined as a fixed silence interval.
Examples of the related art include Japanese Laid-open Patent Publication No. 11-133997.